1#!/usr/bin/env bash 2 3## bash script to generate file magic support for flac. 4## https://github.com/file/file/blob/master/magic/Magdir/audio 5## below "#some common sample rates" (line 471), ie: 6## >>17 belong&0xfffff0 0x2ee000 \b, 192 kHz 7 8LANG=C 9 10target=magic/Magdir/audio 11 12## construct static list of sample rates based on standard crystal 13## oscillator frequencies. 14## 16.384 MHz Unknown audio application 15## (16384 kHz = 32 kHz * 512 = 32 * 2^9) 16## 22.5792 MHz Redbook/CD 17## (22579.2 kHz = 44.1kHz * 512 = 44.1 * 2^9) 18## also used: 11.2896, 16.9344, 33.8688 and 45.1584 19## 24.576 MHz DAT/Video 20## (24576 kHz = 48 kHz * 512 = 48 * 2^9) 21## also used: 49.1520 22 23## 33.8688 > 16.9344 24## 36.864 > 18.432000 25declare -a a_ground_fs=(16384000 22579200 24576000) 26 27## multiply ground clock frequencies by 1953 to get usable base 28## frequencies, for instance: 29## DAT/video: 24.576 MHz * 1000000 / 512 = 48000Hz 30## Redbook/CD: 22.5792 MHz * 1000000 / 512 = 44100Hz 31## use base rates for calculating derived rates 32declare -a samplerates 33## min divider: fs/n 34def_fs_n=512 35min_fs_n=4 36## start at base_fs/(def_fs*min_fs) 37## add each derived sample rate to the array 38for base_fs in "${a_ground_fs[@]}"; do 39 min_fs=$( echo "${base_fs} / ( ${def_fs_n} * ${min_fs_n} )" | bc) 40 ## max multiplier: fs*n*min_fs 41 max_fs_n=$(( 8 * min_fs_n )) 42 n=${max_fs_n} 43 while [[ ${n} -ge 1 ]]; do 44 sample_rate=$(( min_fs * n )) 45 samplerates+=(${sample_rate}) 46 n=$(( n / 2 )) 47 done 48done 49 50declare -a stripped_rates 51declare -a lines 52for samplerate in "${samplerates[@]}"; do 53 ## use bc with sed to convert and format Hz to kHz 54 stripped_rate="$(LANG=C bc <<< "scale=5; ${samplerate} / 1000" | \ 55 sed 's#[0\.]*$##g')" 56 ## only add uniq sample rates (should be necessary 57 if [[ ! "${stripped_rates[@]}" =~ ${stripped_rate} ]]; then 58 printf -v line ">>17\tbelong&%#-15x\t%#08x\t%s, %s kHz\n" \ 59 "16777200" \ 60 "$(( samplerate * 16 ))" \ 61 "\b" \ 62 "${stripped_rate}" 63 stripped_rates+=("${stripped_rate}") 64 lines+=("${line}") 65 fi 66 67done 68printf "## start cutting >>> \n" 69## print out the formatted lines 70printf "%s" "${lines[@]}" | sort -k5 -n 71printf "## <<< stop cutting\n" 72